Risk Factors for Development of Vent Pecking and Cannibalism in Free-range and Organic Laying Hens

A new study from the University of Bristol confirms the link between severe feather pecking and vent pecking or cannibalism and identifies some management factors that appear to increase the likelihood of these undesirable behaviours.
calendar icon 6 April 2015
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Injurious pecking remains one of the biggest animal welfare and economic challenges for free-range egg producers, according to Sarah Lambton at the University of Bristol in the UK and co-authors there and with Stonegate Farmers.

They explain in a paper in Animal Welfare that their prospective epidemiological study investigated the development of vent pecking (VP) and cannibalism on 62 free-range and organic UK farms (119 flocks).

Flocks were visited at 25 (±5) and 40 (±5) weeks of age. Rates of VP were recorded and farmers were asked whether they had observed cannibalism in their flocks. Environmental and management data were collected for each flock. Risk factors associated with these behaviours were modelled using MLwiN.

VP was observed in 19.5 and 29.9 per cent of flocks, at mean rates of 0.35 and 0.21 bouts per bird per hour at 25 and 40 weeks, respectively.

Cannibalism was reported at 22.6 per cent of visits.

The odds of flocks showing VP or cannibalism increased with rate of severe feather pecking (SFP).

VP was more likely to be observed in laying houses with more and/or longer pop holes and where feed was scattered on the floor.

Providing more aerial perch length, or perches more than 500cm in height, was associated with increased risk of VP.

When SFP was excluded from the model, the likelihood of VP was higher in flocks fed pelleted feed.

All of these may provide a useful basis from which to derive management strategies to reduce the risk of VP and thus improve the welfare of laying hens, concluded Lambton and co-authors.

However, they added, it is important to remember that this study does not elucidate the causal relationships between these variables, and further work is needed to understand the mechanism behind these associations.


Lambton S.L., T.G. Knowles, C. Yorke and C.J. Nicol. 2015. The risk factors affecting the development of vent pecking and cannibalism in free-range and organic laying hens. Animal Welfare. 24:101-111. doi: 10.7120/09627286.24.1.101

April 2015

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